Hydrocracking process using a zeolite modified by basic treatment

ABSTRACT

The present invention describes a hydrocracking and/or hydrotreatment process using a catalyst comprising an active phase containing at least one hydrogenating/dehydrogenating component selected from the group VIB elements and the non-precious elements of group VIII of the periodic table, used alone or in a mixture, and a support comprising at least one dealuminated zeolite Y having an overall initial atomic ratio of silicon to aluminum between 2.5 and 20, an initial weight fraction of extra-lattice aluminum atoms greater than 10%, relative to the total weight of aluminum present in the zeolite, an initial mesopore volume measured by nitrogen porosimetry greater than 0.07 ml·g −1  and an initial crystal lattice parameter a 0  between 24.38 Å and 24.30 Å, said zeolite being modified by a) a stage of basic treatment comprising mixing said dealuminated zeolite Y with a basic aqueous solution, and at least one stage c) of thermal treatment.

This application is a divisional application of U.S. patent applicationSer. No. 12/942,351, filed on Nov. 9, 2010.

TECHNICAL FIELD

The present invention relates to a process of hydroconversion and inparticular a hydrocracking and/or hydrotreatment process using acatalyst comprising an active phase containing at least onehydrogenating/dehydrogenating component selected from the group VIBelements and the non-precious elements of group VIII of the periodictable, used alone or in a mixture, and a support comprising at least onedealuminated zeolite Y having an overall initial atomic ratio of siliconto aluminium between 2.5 and 20, an initial weight fraction ofextra-lattice aluminium atoms greater than 10%, relative to the totalweight of aluminium present in the zeolite, an initial mesopore volumemeasured by nitrogen porosimetry greater than 0.07 ml·g⁻¹, and aninitial crystal lattice parameter a₀, between 24.38 Å and 24.30 Å, saidzeolite being modified by a) a stage of basic treatment consisting ofmixing said dealuminated zeolite Y with a basic aqueous solution, and atleast one stage c) of thermal treatment, said catalyst being a sulphidephase catalyst.

In particular, the invention relates to the hydrocracking of hydrocarbonfeeds containing for example aromatic, and/or olefinic, and/ornaphthenic, and/or paraffinic compounds apart from feeds originatingfrom the Fischer-Tropsch process and optionally containing metals,and/or nitrogen, and/or oxygen and/or sulphur.

The objective of the hydrocracking process is essentially the productionof middle distillates, i.e. a kerosene cut having a boiling pointbetween 150 and 250° C., and a diesel fuel cut having a boiling pointbetween 250 and 380° C.

PRIOR ART

Hydrocracking of heavy petroleum fractions is a very important refiningprocess, which makes it possible to produce, from surplus heavy feedsthat are not readily upgradable, lighter fractions such as gasolines,jet fuels and light diesel fuels that the refiner requires for adaptinghis output to the structure of demand. Certain hydrocracking processescan also give a greatly purified residue, which can provide an excellentbase for oils. Relative to catalytic cracking, the advantage ofcatalytic hydrocracking is that it supplies middle distillates of verygood quality. Conversely, the gasoline produced has a much lower octanenumber than that resulting from catalytic cracking.

Hydrocracking is a process that derives its flexibility from three mainelements, namely: the operating conditions used, the types of catalystsused and the fact that the hydrocracking of hydrocarbon feeds can becarried out in one or two stages.

The hydrocracking catalysts used in hydrocracking processes are all ofthe bifunctional type combining an acid function with a hydrogenatingfunction. The acid function is supplied by supports, the surface areasof which are generally in the range from 150 to 800 m²·g⁻¹ and havesurface acidity, such as halogenated (in particular chlorinated orfluorinated) aluminas, combinations of oxides of boron and of aluminium,amorphous silica-aluminas and zeolites. The hydrogenating function issupplied either by one or more metals of group VIB of the periodic tableof the elements, or by a combination of at least one metal of group VIBof the periodic table and at least one group VIII metal.

The distance between the two functions—acid and hydrogenating—is one ofthe parameters governing the activity and selectivity of the catalyst. Aweak acid function and a strong hydrogenating function give catalysts oflow activity, generally working at high temperature (greater than orequal to 390-400° C.), and at a low hourly space velocity (HSV expressedin volume of feed to be treated per unit volume of catalyst and per houris generally less than or equal to 2), but have very good selectivityfor middle distillates (jet fuels and diesel fuels). Conversely, astrong acid function and a weak hydrogenating function give catalyststhat are active, but have poorer selectivity for middle distillates.

One type of conventional hydrocracking catalyst is based on amorphoussupports that are moderately acidic, such as silica-aluminas forexample. These systems are used for producing middle distillates of goodquality, and optionally oil bases. These catalysts are for example usedin single-stage processes. A drawback of these catalysts based on anamorphous support is their low activity.

For their part, catalysts comprising for example zeolite Y of thestructural type FAU display catalytic activity that is greater than thatof silica-aluminas, but have lower selectivity for middle distillates(jet fuels and diesel fuels). This difference is attributed to thedifference in strength of the acid sites on the two types of materials.

Modification of zeolites by alkaline treatment is a process that hasbeen investigated in the literature that is in the public domain. Thisprocess of modification by alkaline treatment makes it possible tocreate mesoporosity in certain types of zeolites such as microporouszeolite ZSM-5 in Ogura et al., Applied Catal. A: General, 219 (2001) 33,Groen et al., Colloids and surfaces A: Physicochem. Eng. Aspects 241(2004) 53, and Groen et al., Microporous and Mesoporous Materials, 69(2004) 29, FER in Groen et al, Microporous and Mesoporous Materials, 69(2004) 29, MOR in Groen et al., Microporous and Mesoporous Materials, 69(2004) 29 and Groen et al., J. Catal. 243 (2006) 212 or zeolite BEA,Groen et al., Microporous and Mesoporous Materials, 69 (2004) 29, Groenet al., J. Catal. 243 (2006) 212 and Groen et al., Microporous andMesoporous Materials, 114 (2008) 93 and the catalysts obtained were usedfor various catalytic reactions. These studies show that alkalinetreatment makes it possible to withdraw silicon atoms from thestructure, thus creating mesoporosity. The creation of mesoporositywhile maintaining crystallinity and acidic properties of the zeolite areidentified in these publications as being connected with the initialoverall Si/Al molar ratio of the zeolites, said optimum overall Si/Alratio having to be between 20 and 50. In fact, outside of this range ofoverall Si/Al ratio between 20 and 50, and for example for an overallSi/Al ratio less than 20, the structure of the zeolite is very stableowing to the presence of a large number of aluminium atoms, whichprevent extraction of silicon atoms and therefore the creation ofadditional mesoporosity.

BENEFIT OF THE INVENTION

The dealuminated zeolite Y contains mesopores, created by extractingaluminium atoms from the framework of the zeolite. The presence ofmesopores makes it possible to improve the selectivity for middledistillates of hydrocracking catalysts using such a zeolite, byfacilitating the diffusion of the primary reaction products (jet fuelsand diesel fuels) and thus limiting overcracking to light products.However, extraction of aluminium atoms from the framework lowers theBrønsted acidity of said zeolite and therefore its catalytic activity.The gain in selectivity for middle distillates connected with themesoporosity of the zeolite is therefore obtained at the expense ofcatalytic activity.

The research carried out by the applicant into the modification ofnumerous zeolites and crystalline microporous solids and hydrogenatingactive phases led him to discover that, surprisingly, a catalyst used ina process for hydrocracking and/or hydrotreatment of hydrocarbon feedscomprising an active phase containing at least onehydrogenating/dehydrogenating component selected from the group VIBelements and the non-precious elements of group VIII of the periodictable, used alone or in a mixture, and a support comprising at least onedealuminated zeolite Y and containing a specific weight fraction ofextra-lattice aluminium atoms, said zeolite being modified by a) a stageof basic treatment consisting of mixing said dealuminated zeolite Y witha basic aqueous solution making it possible to withdraw silicon atomsfrom the structure and insert extra-lattice aluminium atoms in theframework of the zeolite, and at least one stage c) of thermaltreatment, said catalyst being a sulphide phase catalyst, made itpossible to obtain a higher activity, i.e. a higher level of conversion,in hydrocracking and/or in hydrotreatment, and higher selectivity formiddle distillates (kerosene and diesel fuels).

Without being bound by any theory, basic treatment of dealuminatedzeolite containing a specific initial weight fraction of extra-latticealuminium atoms permits the creation of mesopores forming a network ofinterconnected mesopores as far as the surface of the zeolite crystals,by desilication, i.e. by extraction of silicon atoms from the frameworkof the initial zeolite. The creation of mesoporosity accessible from theexternal surface of the zeolite crystals, promoting intercrystallinediffusion of molecules, makes it possible for a catalyst using saidmodified zeolite according to the invention, used in a process for theproduction of middle distillates, to obtain a higher selectivity formiddle distillates. Moreover, basic treatment also permitsrealumination, i.e. reintroduction of at least a proportion of theextra-lattice aluminium atoms present in the initial zeolite into theframework of the modified zeolite, said realumination making it possibleto increase the Brønsted acidity of the modified zeolite, which isreflected, for a catalyst using said modified zeolite according to theinvention, in improved catalytic properties, i.e. better conversion.

An objective of the invention is therefore to supply a process forhydrocracking and/or hydrotreatment of hydrocarbon feeds using acatalyst based on a modified zeolite by a basic treatment that makes itpossible to achieve a higher degree of conversion as well as betterselectivity for middle distillates.

Another objective of the invention is to supply a process for themodification of a dealuminated zeolite Y comprising a) a stage of basictreatment consisting of mixing said dealuminated zeolite Y with a basicaqueous solution, said basic aqueous solution being a solution of basiccompounds selected from alkaline bases and strong non-alkaline bases,said stage a) being carried out at a temperature between 40 and 100° C.and for a duration between 5 minutes and 5 h and at least one stage c)of thermal treatment carried out at a temperature between 200 and 700°C.

Another objective of the invention is to supply a catalyst having anactive phase comprising at least one hydrogenating/dehydrogenatingcomponent selected from the group VIB elements and the non-preciouselements of group VIII of the periodic table, used alone or in amixture, and a support comprising at least one dealuminated zeolite Yhaving an overall initial atomic ratio of silicon to aluminium between2.5 and 20, an initial weight fraction of extra-lattice aluminium atomsgreater than 10%, relative to the total weight of aluminium present inthe zeolite, an initial mesopore volume measured by nitrogen porosimetrygreater than 0.07 ml·g⁻¹, and an initial crystal lattice parameter a₀between 24.38 Å and 24.30 Å, said zeolite being modified by amodification process comprising a) a stage of basic treatment consistingof mixing said dealuminated zeolite Y with a basic aqueous solution,said basic aqueous solution being a solution of basic compounds selectedfrom alkaline bases and strong non-alkaline bases, said stage a) beingcarried out at a temperature between 40 and 100° C. and for a durationbetween 5 minutes and 5 h and at least one stage c) of thermal treatmentcarried out at a temperature between 200 and 700° C., said catalystbeing a sulphide phase catalyst.

DETAILED DESCRIPTION OF THE CATALYST ACCORDING TO THE INVENTION

According to the invention, the process uses a catalyst comprising anactive phase comprising at least one hydrogenating/dehydrogenatingcomponent selected from the group VIB elements and the non-preciouselements of group VIII of the periodic table, used alone or in amixture, said catalyst being a sulphide phase catalyst.

The Hydrogenating Phase

Preferably, the group VIB elements of the periodic table are selectedfrom the group formed by tungsten and molybdenum, used alone or in amixture. According to a preferred embodiment, thehydrogenating/dehydrogenating element selected from the group formed bythe group VIB elements of the periodic table is molybdenum. According toanother preferred embodiment, the hydrogenating/dehydrogenating elementselected from the group formed by the group VIB elements of the periodictable is tungsten.

Preferably, the non-precious elements of group VIII of the periodictable are selected from the group formed by cobalt and nickel, usedalone or in a mixture. According to a preferred embodiment, thehydrogenating/dehydrogenating element selected from the group formed bynon-precious group VIII elements is cobalt. According to anotherpreferred embodiment, the hydrogenating/dehydrogenating element selectedfrom the group formed by non-precious group VIII elements is nickel.

Preferably, said catalyst comprises at least one metal of group VIB incombination with at least one non-precious metal of group VIII, thenon-precious group VIII elements being selected from the group formed bycobalt and nickel, used alone or in a mixture, and the group VIBelements being selected from the group formed by tungsten andmolybdenum, used alone or in a mixture.

Advantageously, the following combinations of metals are used:nickel-molybdenum, cobalt-molybdenum, nickel-tungsten, cobalt-tungsten,the preferred combinations being: nickel-molybdenum, cobalt-molybdenum,cobalt-tungsten, nickel-tungsten and even more advantageouslynickel-molybdenum and nickel-tungsten.

In the case where the catalyst comprises at least one metal of group VIBin combination with at least one non-precious metal of group VIII, thecontent of metal of group VIB, in oxide equivalent, is advantageouslybetween 5 and 40 wt. % relative to the total weight of said catalyst,preferably between 10 and 35 wt. % and very preferably between 15 and 30wt. % and the content of non-precious metal of group VIII, in oxideequivalent, is advantageously between 0.5 and 10 wt. % relative to thetotal weight of said catalyst, preferably between 1 and 8 wt. % and verypreferably between 1.5 and 6 wt. %.

It is also possible to use combinations of three metals for examplenickel-cobalt-molybdenum, nickel-molybdenum-tungsten,nickel-cobalt-tungsten.

Advantageously, the following combinations of metals are used:nickel-niobium-molybdenum, cobalt-niobium-molybdenum,nickel-niobium-tungsten, cobalt-niobium-tungsten, the preferredcombinations being: nickel-niobium-molybdenum,cobalt-niobium-molybdenum. It is also possible to use combinations offour metals, for example nickel-cobalt-niobium-molybdenum.

The catalyst can also advantageously contain:

-   -   from 0 to 20 wt. %, preferably from 0.1 to 15 wt. % and even        more preferably 0.1 to 10 wt. %, relative to the total weight of        the catalyst, of at least one doping element selected from the        group constituted by silicon, boron and phosphorus, not        including the silicon contained in the framework of the zeolite        and optionally    -   from 0 to 60 wt. %, preferably from 0.1 to 50 wt. %, and even        more preferably 0.1 to 40 wt. %, relative to the total weight of        the catalyst, of at least one element selected from group VB and        preferably niobium and also optionally    -   from 0 to 20 wt. %, preferably from 0.1 to 15 wt. % and even        more preferably 0.1 to 10 wt. % relative to the total weight of        the catalyst, of at least one element selected from group VIIA,        preferably fluorine.

According to the invention, the catalyst used in the process accordingto the invention has a support comprising at least one modified zeoliteaccording to the invention and advantageously a porous mineral matrix ofthe oxide type, said support comprising and preferably being constitutedby, preferably:

-   -   0.1 to 99.8 wt. %, preferably from 0.1 to 80 wt. %, even more        preferably 0.1 to 70 wt. %, and very preferably 0.1 to 50 wt. %        of modified zeolite according to the invention relative to the        total weight of the catalyst,    -   0.2 to 99.9 wt. %, preferably from 20 to 99.9%, more preferably        from 30 to 99.9 wt. %, and very preferably from 50 to 99.9 wt.        %, relative to the total weight of the catalyst, of at least one        porous mineral matrix of the oxide type.        The Zeolite According to the Invention

According to the invention, the zeolite initially used, suitable for theapplication of the catalyst support used in the process forhydrocracking and/or hydrotreatment of hydrocarbon feeds, isdealuminated zeolite Y (USY) of the structural type FAU.

According to the invention, the dealuminated initial zeolite Y suitablefor the application of the catalyst support used in the process forhydrocracking and/or hydrotreatment of hydrocarbon feeds has, before itis modified, an initial overall atomic ratio of silicon to aluminiumbetween 2.5 and 20.0, preferably between 2.6 and 12.0 and morepreferably between 2.7 and 10.0, an initial weight fraction ofextra-lattice aluminium atoms greater than 10%, preferably greater than20% and more preferably greater than 30 wt. % relative to the totalweight of aluminium present in the zeolite, an initial mesopore volumemeasured by nitrogen porosimetry greater than 0.07 ml·g⁻¹, preferablygreater than 0.10 ml·g⁻¹, and more preferably greater than 0.13 ml·g⁻¹and an initial crystal lattice parameter a₀ between 24.38 Å and 24.30 Å.

Preferably, the dealuminated initial zeolite Y suitable for theapplication of the catalyst support used in the hydrocracking and/orhydrotreatment process according to the invention has, before it ismodified, an initial micropore volume measured by nitrogen porosimetrygreater than 0.20 ml·g⁻¹, and preferably greater than 0.25 ml·g⁻¹.

According to the invention, said dealuminated initial zeolite Y havingan overall initial atomic Si/Al ratio between 2.5 and 20.0, preferablybetween 2.6 and 12.0 and more preferably between 2.7 and 10.0, saidoverall atomic ratio Si/Al being measured by X-ray fluorescence (XF) andhaving an initial weight fraction of extra-lattice aluminium atomsmeasured by NMR of the aluminium that is greater than 10%, preferablygreater than 20% and more preferably greater than 30 wt. % relative tothe total weight of aluminium present in the zeolite, is obtained bydealumination of a zeolite Y of the structural type FAU by any method ofdealumination known to a person skilled in the art.

Production of the Dealuminated Initial Zeolite Y

The zeolite Y of the structural type FAU, which is advantageously in theNaY form after synthesis, can advantageously undergo one or more ionexchanges before undergoing the dealumination stage.

The treatment of dealumination of the zeolite Y of the structural typeFAU generally having an overall atomic ratio Si/Al after synthesisbetween 2.3 and 2.8 can advantageously be carried out by all the methodsknown to a person skilled in the art. Preferably, dealumination iscarried out by a thermal treatment in the presence of steam (also calledsteaming) and/or by one or more acid attacks advantageously carried outby treatment with an aqueous solution of mineral or organic acid.Preferably, dealumination is carried out by a thermal treatment followedby one or more acid attacks or only by one or more acid attacks.Preferably, the thermal treatment in the presence of steam to which thezeolite Y is subjected is carried out at a temperature between 200 and900° C., preferably between 300 and 900° C., even more preferablybetween 400 and 750° C. The duration of said thermal treatment isadvantageously greater than or equal to 0.5 h, preferably between 0.5 hand 24 h, and very preferably between 1 h and 12 h. The percentage byvolume of steam during the thermal treatment is advantageously between 5and 100%, preferably between 20 and 100%, more preferably between 40%and 100%. The volume fraction other than steam optionally present isformed of air. The gas flow formed of steam and optionally of air isadvantageously between 0.2 L/h/g and 10 L/h/g of zeolite Y.The thermal treatment makes it possible to extract the aluminium atomsfrom the framework of the zeolite Y while keeping the overall atomicratio Si/Al of the treated zeolite unchanged. The thermal treatment inthe presence of steam is advantageously repeated as many times asnecessary to obtain the dealuminated initial zeolite Y suitable for theapplication of the catalyst support used in the process according to theinvention having the desired characteristics and in particular a weightfraction of extra-lattice aluminium atoms representing more than 10 wt.% relative to the total weight of aluminium present in said zeolite. Thenumber of thermal treatments is advantageously less than 4 andpreferably a single thermal treatment is carried out, at the end ofwhich the initial weight fraction of extra-lattice aluminium atoms ismeasured by NMR of the aluminium.

Carrying out the dealumination of the zeolite Y, and to adjust theoverall atomic ratio Si/Al of the dealuminated zeolite Y to a valuebetween 2.5 and 20 according to the invention, requires appropriateselection and control of the operating conditions of each stage of acidattack. In particular, the temperature at which the treatment withaqueous solution of mineral or organic acid is carried out, the natureand concentration of the acid used, the ratio of the quantity of acidsolution to the weight of zeolite treated, the duration of the treatmentby acid attack and the number of treatments carried out are significantparameters for the application of each stage of acid attack.

The acid selected for the application of said stage of acid attack isadvantageously either a mineral acid or an organic acid, preferably theacid is a mineral acid selected from nitric acid HNO₃, hydrochloric acidHCl and sulphuric acid H₂SO₄. Very preferably, the acid is nitric acid.When an organic acid is used for acid attack, acetic acid CH₃CO₂H ispreferred.

Preferably, the acid attack treatment of zeolite Y with an aqueoussolution of a mineral acid or of an organic acid is carried out at atemperature between 30° C. and 120° C., preferably between 50° C. and120° C., and more preferably between 60 and 100° C. The concentration ofacid in the aqueous solution is advantageously between 0.05 and 20mol·L⁻¹, preferably between 0.1 and 10 mol·L⁻¹, and more preferablybetween 0.5 and 5 mol·L⁻¹. The ratio of the volume of acid solution V inml to the weight W of zeolite Y treated in grams is advantageouslybetween 1 and 50, and preferably between 2 and 20. The duration of acidattack is advantageously greater than 1 h, preferably between 2 h and 10h, and more preferably between 2 h and 8 h. The number of successivetreatments of acid attack of zeolite Y with an aqueous acid solution isadvantageously less than 4. In the case where several successivetreatments of acid attack are carried out, aqueous solutions of mineralor organic acid with different concentrations of acid can be used.In order to adjust the overall atomic ratio Si/Al of dealuminatedzeolite Y to a value between 2.5 and 20, said ratio is measured by X-rayfluorescence at the end of each acid attack treatment that is carriedout.

After carrying out the acid attack treatment(s), the zeolite is thenadvantageously washed with distilled water and is then dried at atemperature between 80 and 140° C. for a duration between 10 and 48 h.

The treatment by acid attack makes it possible both to extract aluminiumatoms from the framework and extract the aluminium atoms from the poresof the zeolitic solid. Thus, the overall atomic ratio Si/Al of thedealuminated zeolite Y obtained increases to a value between 2.5 and 20,said zeolite being suitable for the application of the catalyst supportused in the process according to the invention.

Moreover, said dealuminated initial zeolite Y obtained, and suitable forthe application of the catalyst support used in the process according tothe invention, has after dealumination an initial mesopore volumemeasured by nitrogen porosimetry greater than 0.07 ml·g⁻¹, preferablygreater than 0.10 ml·g⁻¹ and preferably greater than 0.13 ml·g⁻¹, thecreation of mesoporosity resulting from extraction of aluminium atomsout of the pores of the zeolite solid and an initial crystal latticeparameter a₀ between 24.38 Å and 24.30 Å.

Said dealuminated initial zeolite Y obtained advantageously also has aninitial micropore volume measured by nitrogen porosimetry greater than0.20 ml·g⁻¹, and preferably greater than 0.25 ml·g⁻¹.

The micropore and mesopore volumes of the dealuminated zeolite Y aremeasured by adsorption/desorption of nitrogen and the lattice constantof the zeolite is measured by X-ray diffraction (XRD).

Another object of the present invention is a process for modifying adealuminated zeolite Y comprising a) a stage of basic treatmentconsisting of mixing said dealuminated zeolite Y with a basic aqueoussolution, said basic aqueous solution being a solution of basiccompounds selected from alkaline bases and strong non-alkaline bases,said stage a) being carried out at a temperature between 40 and 100° C.and for a duration between 5 minutes and 5 h and at least one stage c)of thermal treatment carried out at a temperature between 200 and 700°C.

Process for Modifying the Dealuminated Initial Zeolite Y According tothe Invention

In accordance with the invention, the dealuminated initial zeolite Ysuitable for the application of the catalyst support used in the processaccording to the invention is modified by a specific modifying processcomprising a) a stage of basic treatment consisting of mixing saiddealuminated zeolite Y with a basic aqueous solution, said basic aqueoussolution being a solution of basic compounds selected from alkalinebases and strong non-alkaline bases, said stage a) being carried out ata temperature between 40 and 100° C. and for a duration between 5minutes and 5 h and at least one stage c) of thermal treatment carriedout at a temperature between 200 and 700° C.

Stage a) of basic treatment makes it possible to withdraw silicon atomsfrom the structure and insert extra-lattice aluminium atoms in theframework.

According to the invention, the process for modifying said dealuminatedinitial zeolite Y comprises a stage a) of basic treatment consisting ofmixing said dealuminated zeolite USY with a basic aqueous solution, saidbasic aqueous solution being a solution of basic compounds selected fromalkaline bases and strong non-alkaline bases, said stage a) beingcarried out at a temperature between 40 and 100° C. and for a durationbetween 5 minutes and 5 h.

The basic compounds selected from alkaline bases are preferably selectedfrom alkali metal carbonates and alkali metal hydroxides, the alkalinecations of alkali metal carbonates and of alkali metal hydroxidesbelonging advantageously to groups IA or IIA of the periodic table andthe strong non-alkaline bases are preferably selected from quaternaryammoniums used alone or in a mixture, and preferably the non-alkalinestrong base is tetramethylammonium hydroxide.Said alkaline cations of alkali metal carbonates and of alkali metalhydroxides belonging advantageously to groups IA or IIA of the periodictable are preferably selected from the cations Na⁺, Li⁺, K⁺, Rb⁺, Cs⁺,Ba²⁺ and Ca²⁺ and very preferably said cation is the cation Na⁺ or K⁺.Preferably, the aqueous solution is a solution of sodium carbonate orsodium hydroxide and more preferably the aqueous solution is a solutionof sodium hydroxide.Said basic aqueous solution has a concentration between 0.001 mol/L and12 mol/L, preferably a concentration between 0.005 mol/L and 11 mol/Land even more preferably a concentration between 0.01 mol/L and 9 mol/L.According to the invention, stage a) of basic treatment of the processfor modifying said dealuminated initial zeolite USY is carried out undertemperature conditions between 40 and 100° C. (reflux) and preferablybetween 40 and 90° C. and for a duration between 5 min and 5 h,preferably between 15 min and 4 h and even more preferably between 15min and 3 h.

On completion of the basic treatment of said zeolite, the solution iscooled rapidly to ambient temperature and then said zeolite is separatedfrom the liquid by any technique known to a person skilled in the art.The separation can be carried out by filtration or by centrifugation,and preferably by centrifugation. The modified zeolite USY obtained isthen washed with distilled water at a temperature between 20 and 100° C.and preferably at a temperature between 40 and 80° C. and verypreferably at 50° C. and is dried at a temperature between 80 and 150°C. and preferably between 100 and 130° C. and very preferably at 120° C.

In the case where stage a) of basic treatment consists of mixing saiddealuminated initial zeolite Y with a basic aqueous solution ofcompounds selected from alkaline bases, the zeolite contained in thecatalyst support used in the process according to the inventioncontains, at the end of stage a) of the modification process, a partialor complete fraction of alkaline ions in the cationic position.

In the case where stage a) of basic treatment consists of mixing saiddealuminated initial zeolite Y with a basic aqueous solution ofcompounds selected from non-alkaline bases, the zeolite contained in thecatalyst support used in the process according to the inventioncontains, at the end of stage a) of the modification process, a partialor complete fraction of quaternary ammonium ions in the cationicposition.

During stage a) of basic treatment of the process for modifying thedealuminated initial zeolite Y according to the invention, a proportionof the silicon atoms contained in the framework of said zeolite areextracted, a phenomenon called desilication, creating voids in thestructure and the formation of mesoporosity and/or permittingreinsertion of at least a proportion of the fraction of extra-latticealuminium atoms present in said dealuminated initial zeolite Y, in placeof the silicon atoms extracted by desilication and thus permitting theformation of new Brønsted acid sites. This second phenomenon is calledre-alumination.

In the case where stage a) of basic treatment consists of mixing saiddealuminated initial zeolite USY with a basic aqueous solution of basiccompounds selected from alkaline bases and preferably selected fromalkali metal carbonates and alkali metal hydroxides and very preferablywith a solution of sodium hydroxide (NaOH), the process for modifyingsaid dealuminated initial zeolite USY advantageously includes a stage b)of at least one partial or complete exchange of said alkaline cationsbelonging to groups IA and IIA of the periodic table introduced duringstage a) and present in the cationic position, with NH₄ ⁺ cations andpreferably Na⁺ cations with NH₄ ⁺ cations.

Partial or complete exchange of the alkaline cations with NH₄ ⁺ cationsmeans exchange from 80 to 100%, preferably 85 to 99.5% and morepreferably 88 to 99%, of said alkaline cations with NH₄ ⁺ cations. Thequantity of alkaline cations remaining and preferably the quantity ofNa⁺ cations remaining in the modified zeolite, relative to the quantityof NH₄ ⁺ cations initially present in the zeolite is, at the end ofstage b), advantageously between 0 and 20%, preferably between 0.5 and15% and preferably between 1 and 12%.

Preferably, for this stage, several ion exchange(s) are carried out witha solution containing at least one ammonium salt selected from theammonium chlorate, sulphate, nitrate, phosphate, or acetate salts, so asto remove, at least partly, the alkaline cations and preferably Na⁺cations present in the zeolite. Preferably, the ammonium salt isammonium nitrate NH₄NO₃.

Thus, the content of alkaline cations remaining and preferably of Na⁺cations in the modified zeolite at the end of stage b) is preferablysuch that the molar ratio of alkaline cation to aluminium and preferablythe Na/Al molar ratio is between 0.2:1 and 0:1, preferably between0.15:1 and 0.005:1, and more preferably between 0.12:1 and 0.01:1.

The desired Na/Al ratio is obtained by adjusting the NH₄ ⁺ concentrationof the cation exchange solution, the temperature of cation exchange andthe cation exchange number. The concentration of NH₄ ⁺ in the solutionvaries advantageously between 0.01 and 12 mol/L, and preferably between1 and 10 mol/L. The temperature of the exchange stage is advantageouslybetween 20 and 100° C., preferably between 60 and 95° C., preferablybetween 60 and 90° C., more preferably between 60 and 85° C. and evenmore preferably between 60 and 80° C. The cation exchange number variesadvantageously between 1 and 10 and preferably between 1 and 4.

In the case where stage a) of basic treatment consists of mixing saiddealuminated initial zeolite USY with an aqueous solution of basiccompounds selected from strong non-alkaline bases preferably selectedfrom quaternary ammoniums used alone or in a mixture and preferably thenon-alkaline strong base being tetramethylammonium hydroxide, themodified zeolite obtained from stage a) contains a partial or completefraction of quaternary ammonium ions in the cationic position.

In this case, the process for modifying said dealuminated initialzeolite USY advantageously does not include stage b) of at least onepartial or complete intermediate exchange, and the modified zeoliteobtained from stage a) directly undergoes stage c) of thermal treatment.

According to the invention, the process for modifying the dealuminatedinitial zeolite Y then has at least one stage c) of thermal treatment.

In the case where stage a) of basic treatment consists of mixing saiddealuminated initial zeolite USY with a basic aqueous solution ofcompounds selected from alkaline bases and preferably selected fromalkali metal carbonates and alkali metal hydroxides and very preferablywith a solution of sodium hydroxide (NaOH), stage c) of thermaltreatment permits, at the same time, drying and the conversion of theNa₄ ⁺ cations exchanged during stage b) to protons.In the case where stage a) of basic treatment consists of mixing saiddealuminated initial zeolite USY with a basic aqueous solution ofcompounds selected from strong non-alkaline bases and preferablyselected from quaternary ammoniums used alone or in a mixture andpreferably the non-alkaline strong base being tetramethylammoniumhydroxide, stage c) of thermal treatment permits, at the same time,drying and the decomposition of the ammonium quaternary cations in theposition of counter-ions and the formation of protons.In all cases, at the end of said stage c) of thermal treatment, theprotons of the zeolite are partially or completely regenerated.

Stage c) of thermal treatment according to the invention is carried outat a temperature between 200 and 700° C., and preferably between 300 and500° C. Said stage of thermal treatment is advantageously implementedunder air, under oxygen, under hydrogen, under nitrogen or under argonor under a mixture of nitrogen and argon. The duration of said treatmentis advantageously between 1 and 5 hours.

Another object of the present invention is a modified dealuminatedzeolite Y obtained by the process for modifying according to theinvention.

At the end of the process of modification according to the invention,the final modified zeolite implemented in the catalyst support used inthe process according to the invention advantageously has a finalmesopore volume measured by nitrogen porosimetry at least 10% greaterrelative to the initial mesopore volume and preferably at least 20%greater relative to the initial mesopore volume of the dealuminatedinitial zeolite USY, a final micropore volume measured by nitrogenporosimetry that must not decrease by more than 40%, preferably by morethan 30% and preferably by more than 20% relative to the initialmicropore volume of said dealuminated initial zeolite USY, a Brønstedacidity more than 10% higher and preferably more than 20% higherrelative to the Brønsted acidity of the dealuminated initial zeolite Yand a final crystal lattice parameter a₀ greater than the initialcrystal lattice parameter a₀) of the dealuminated initial zeolite Y.

At the end of the process for modifying the dealuminated zeolite Yaccording to the invention, the significant increase in the mesoporevolume of the resultant modified zeolite and maintenance of asignificant micropore volume relative to the dealuminated initialzeolite Y reflect the creation of additional mesoporosity bydesilication.

Moreover, the increase in the Brønsted acidity of the final modifiedzeolite relative to the dealuminated initial zeolite Y is evidence ofthe reintroduction of the extra-lattice aluminium atoms into theframework of the zeolite, i.e. the phenomenon of realumination.The Amorphous or Poorly Crystallized Porous Mineral Matrix of the OxideType

The catalyst support used in the hydrocracking and/or hydrotreatmentprocess according to the invention advantageously contains a porousmineral matrix, preferably amorphous, which is advantageouslyconstituted by at least one refractory oxide. Said matrix isadvantageously selected from the group comprising alumina, silica,clays, titanium dioxide, boron oxide and zirconia, used alone or in amixture. The matrix can be constituted by a mixture of at least two ofthe aforementioned oxides, and preferably silica-alumina. Aluminates canalso be selected. It is preferable to use matrices containing alumina,in all its forms known to a person skilled in the art, for example gammaalumina.

Mixtures of alumina and silica, and mixtures of alumina andsilica-alumina can also be used advantageously.

Characterization Techniques

The overall Si/Al atomic ratio of the dealuminated initial and finalzeolite Y, i.e. after modification, is measured by X-ray fluorescence.X-ray fluorescence is a technique for overall elementary analysis whichpermits analysis of all the elements of the periodic table starting fromboron. It is possible to determine from a few ppm up to 100%. In thisinvention, this technique is used for determining the silicon andaluminium in the zeolites (as percentage by weight) and thus makes itpossible to calculate the Si/Al atomic ratio.

The weight fraction of tetracoordinated and hexacoordinated aluminiumatoms present in the modified zeolite USY is determined by nuclearmagnetic resonance of solid ²⁷Al. The use of NMR of aluminium is in factknown for detecting and quantifying the various coordination states ofthis nucleus (“Analyse physico-chimique des catalyseurs industriels”, J.Lynch, Editions Technip (2001) chap. 13, pages 290 and 291). The NMRspectrum of the aluminium in the initial zeolite USY and in the modifiedzeolite USY according to the invention has two signals, one beingcharacteristic of the resonance of the tetracoordinated aluminium atoms(i.e. of the aluminium atoms comprised in the crystal lattice of thezeolite) and the other being characteristic of the resonance of thehexacoordinated aluminium atoms (i.e. of the aluminium atoms outside ofthe crystal lattice or extra-lattice aluminium atoms). Thetetracoordinated aluminium atoms Al_(IV) resonate at a chemical shiftbetween +40 ppm and +75 ppm and the hexacoordinated or extra-latticealuminium atoms Al_(VI) resonate at a chemical shift between −15 ppm and+15 ppm. The weight fraction of the two aluminium species Al_(IV) andAl_(VI) is quantified by integration of the signals corresponding toeach of these species.

More precisely, the modified zeolite USY according to the inventioncontained in the catalyst support according to the invention wasanalysed by NMR-MAS of solid ²⁷Al on a Brücker spectrometer of the typeAvance 400 MHz by means of a 4 mm probe optimized for ²⁷Al. The speed ofrotation of the sample is close to 14 kHz. The aluminium atom is aquadrupole nucleus with spin of 5/2. Under so-called selectiveconditions of analysis, namely a field of low radiofrequency equal to 30kHz, a low pulse angle equal to π/2 and in the presence of awater-saturated sample, the technique of NMR with magic angle spinning(MAS), designated NMR-MAS, is a quantitative technique. Analysis of eachNMR-MAS spectrum gives directly the quantity of different aluminiumspecies, namely of tetracoordinated aluminium atoms Al_(IV) and ofhexacoordinated or extra-lattice aluminium atoms Al_(VI). Each spectrumis adjusted in chemical shift relative to a 1M solution of aluminiumnitrate, for which the signal from aluminium is at zero ppm. The signalscharacterizing the tetracoordinated aluminium atoms Al_(IV) areintegrated between +40 ppm and +75 ppm, which corresponds to area 1, andthe signals characterizing the hexacoordinated aluminium atoms Al_(VI)are integrated between −15 ppm and +15 ppm, which corresponds to area 2.The weight fraction of hexacoordinated aluminium atoms Al_(VI) is equalto the ratio area 2/(area 1+ area 2).

The crystal lattice parameter a₀ of the dealuminated initial and finalzeolites Y, i.e. after modification, is measured by X-ray diffraction(XRD). For zeolite Y of type FAU, the lattice parameter a₀ is calculatedfrom the positions of the peaks corresponding to the Miller indices 533,642 and 555 (“Théorie et technique de la radiocristallographie”, A.Guinier, publ. Dunod, 1964). As the length of the Al—O bond is greaterthan that of the Si—O bond, the parameter a₀ increases with increasingnumber of aluminium atoms in the tetrahedral position in the zeoliteframework. For crystals constituted by cubic lattices such as zeolites Yof type FAU, there is a linear relation between the lattice parameter a₀and the Si/Al ratio (“Hydrocracking Science and Technology”, J.Scherzer, A. J. Gruia, Marcel Dekker Inc., 1996)

The micropore and mesopore volumes of the dealuminated initial and finalzeolite Y are measured by adsorption/desorption of nitrogen. Analysis ofthe curves of nitrogen adsorption isotherms of microporous andmesoporous solids makes it possible to calculate the pore volumes by theso-called volumetric technique. Various types of models can be used. Thepore distribution measured by adsorption of nitrogen was determined bythe Barrett-Joyner-Halenda (B J H) model. The nitrogenadsorption-desorption isotherm according to the B J H model is describedin the article in “The Journal of American Society”, 73, 373, (1951) byE. P. Barrett, L. G. Joyner and P. P. Halenda. Hereinafter, nitrogenadsorption volume means the volume measured for P/P₀=0.95. The microporevolume is obtained by the “t-plot” method or by measuring the volumeadsorbed at P/PO=0.35 (P=adsorption pressure; PO=saturated vapourpressure of the adsorbate at the test temperature). The mesopore volumeis obtained by subtracting the micropore volume from the total porevolume.

The Lewis and Brønsted acidity of the zeolites is measured by adsorptionof pyridine followed by infrared spectroscopy (FTIR). Integration of thecharacteristic bands of pyridine coordinated at 1455 cm⁻¹ and ofpyridine protonated at 1545 cm⁻¹ makes it possible to compare therelative acidity of catalysts of the Lewis and Brønsted type,respectively. Prior to adsorption of pyridine, the zeolite is pretreatedunder high vacuum at 450° C. for 10 h with an intermediate plateau at150° C. for 1 h. The pyridine is then adsorbed at 150° C. and thendesorbed under high vacuum at this same temperature before recording thespectra.

Preparation of the Catalyst

The modified zeolite can be, without this being limitative, for examplein the form of powder, finely-ground powder, suspension, or suspensionthat has undergone a deagglomeration treatment. Thus, for example, themodified zeolite can advantageously be prepared as a suspension,acidified or not, at a concentration adjusted to the intended finalzeolite content on the support. This suspension, commonly called aslurry, is then advantageously mixed with the matrix precursors.

According to a preferred manner of preparation, the modified zeolite canadvantageously be introduced during forming of the support with thematrix constituents. For example, according to this preferred embodimentof the present invention, the modified zeolite according to theinvention is added to a wet alumina gel during the stage of forming ofthe support.

One of the preferred methods of forming of the support in the presentinvention consists of mixing at least one modified zeolite with a wetalumina gel for some tens of minutes, then passing the paste thusobtained through a die to form extrudates with a diameter between 0.4and 4 mm.

According to another preferred manner of preparation, the modifiedzeolite can be introduced during synthesis of the matrix. For example,according to this preferred embodiment of the present invention, themodified zeolite is added during synthesis of the silica-alumina matrix;the zeolite can be added to a mixture composed of an alumina compound inan acid medium with a completely soluble silica compound.

The support can be formed by any technique known to a person skilled inthe art. Forming can be carried out for example by extrusion, bypelletization, by the oil-drop method, by rotating plate granulation orby any other method well known to a person skilled in the art.

At least one calcination can be carried out after any one of thepreparation stages. The calcination treatment is usually carried outunder air at a temperature of at least 150° C., preferably at least 300°C., more preferably between about 350 and 1000° C.

The group VIB elements and/or the non-precious group VIII elements andoptionally doping elements selected from phosphorus, boron, silicon andoptionally elements of groups VB and VIIB can optionally be introduced,wholly or partly, at any stage of preparation, during synthesis of thematrix, preferably during forming of the support, or very preferablyafter forming of the support by any method known to a person skilled inthe art. They can be introduced after forming of the support, eitherafter or before drying and calcination of the support.

According to a preferred embodiment of the present invention, some orall of the elements of groups VIB and/or non-precious group VIIIelements, and optionally doping elements selected from phosphorus,boron, silicon and optionally elements of groups VB and VIIB can beintroduced during forming of the support, for example during the stageof mixing of the modified zeolite with a wet alumina gel.

According to another preferred embodiment of the present invention, someor all of the elements of groups VIB and/or of non-precious group VIIIelements and optionally those selected from phosphorus, boron, siliconand optionally elements of groups VB and VIIA can be introduced by oneor more operations of impregnation of the formed and calcined support,with a solution containing the precursors of said elements. Preferably,the support is impregnated with an aqueous solution. The impregnation ofthe support is preferably carried out by the so-called “dry” method ofimpregnation that is well known to a person skilled in the art.

In the case where the catalyst of the present invention contains anon-precious metal of group VIII, the group VIII metals are preferablyintroduced by one or more operations of impregnation of the formed andcalcined support, after those of group VIB or at the same time as thelatter.

According to another preferred embodiment of the present invention,deposition of boron and silicon can also be carried out simultaneouslyusing for example a solution containing a boron salt and a siliconcompound of the silicone type.

Impregnation of the element or elements of group VB and preferably ofniobium can be facilitated by adding oxalic acid and optionally ammoniumoxalate in the solutions of niobium oxalate. Other compounds can be usedfor improving the solubility and facilitating the impregnation ofniobium, as is well known to a person skilled in the art.

When at least one doping element, P and/or B and/or Si, is introduced,its distribution and its localization can be determined by techniquessuch as the Castaing microprobe (distribution profile of the variouselements), transmission electron microscopy coupled with EDX analysis(energy-dispersion X-ray analysis) of the catalyst components, or bymapping the distribution of the elements present in the catalyst byelectron microprobe.

For example, among the sources of molybdenum and of tungsten, it ispossible to use oxides and hydroxides, molybdic and tungstic acids andtheir salts in particular the ammonium salts such as ammonium molybdate,ammonium heptamolybdate, ammonium tungstate, phosphomolybdic acid,phosphotungstic acid and their salts, silicomolybdic acid,silicotungstic acid and their salts. Oxides and ammonium salts such asammonium molybdate, ammonium heptamolybdate and ammonium tungstate arepreferably used.

The sources of non-precious group VIII elements that can be used arewell known to a person skilled in the art. For example, for the basemetals, the nitrates, sulphates, hydroxides, phosphates, halides forexample chlorides, bromides and fluorides, carboxylates for exampleacetates and carbonates, will be used.

The preferred source of phosphorus is orthophosphoric acid H₃PO₄, butits salts and esters such as ammonium phosphates are also suitable.Phosphorus can for example be introduced in the form of a mixture ofphosphoric acid and a basic organic compound containing nitrogen such asammonia, primary and secondary amines, cyclic amines, the compounds ofthe pyridine family and quinolines and the compounds of the pyrrolefamily. Tungsto-phosphoric or tungsto-molybdic acids can be used.

The phosphorus content is adjusted, without limiting the scope of theinvention, so as to form a mixed compound in solution and/or on thesupport, for example tungsten-phosphorus ormolybdenum-tungsten-phosphorus. These mixed compounds can beheteropolyanions. These compounds can be Anderson heteropolyanions, forexample.

The source of boron can be boric acid, preferably orthoboric acid H₃BO₃,ammonium diborate or pentaborate, boron oxide, boric esters. Boron canfor example be introduced in the form of a mixture of boric acid,hydrogen peroxide and a basic organic compound containing nitrogen suchas ammonia, primary and secondary amines, cyclic amines, compounds ofthe pyridine family and quinolines and compounds of the pyrrole family.Boron can be introduced for example with a solution of boric acid in awater/alcohol mixture.

Numerous sources of silicon can be used. Thus, it is possible to useethyl orthosilicate Si(OEt)₄, siloxanes, polysiloxanes, silicones,emulsions of silicones, silicates of halides such as ammoniumfluorosilicate (NH₄)₂SiF₆ or sodium fluorosilicate Na₂SiF₆.Silicomolybdic acid and its salts, and silicotungstic acid and its saltscan also be used advantageously. Silicon can be added for example by theimpregnation of ethyl silicate in solution in a water/alcohol mixture.Silicon can be added for example by the impregnation of a siliconcompound of the silicone type or silicic acid suspended in water.

The sources of group VB element that can be used are well known to aperson skilled in the art. For example, among the sources of niobium, itis possible to use oxides, such as diniobium pentoxide Nb₂O₅, niobicacid Nb₂O₅·H₂O, niobium hydroxides and polyoxoniobates, niobiumalkoxides of formula Nb(OR1)₃ where R1 is an alkyl radical, niobiumoxalate NbO(HC₂O₄)₅, ammonium niobate. Niobium oxalate or ammoniumniobate is preferably used.

The sources of group VIIA elements that can be used are well known to aperson skilled in the art. For example, fluoride anions can beintroduced in the form of hydrofluoric acid or salts thereof. Thesesalts are formed with alkali metals, ammonium or an organic compound. Inthe latter case, the salt is advantageously formed in the reactionmixture by reaction between the organic compound and hydrofluoric acid.It is also possible to use hydrolysable compounds, which can releasefluoride anions in water, such as ammonium fluorosilicate (NH₄)₂SiF₆,silicon tetrafluoride SiF₄ or sodium tetrafluoride Na₂SiF₆. Fluorine canbe introduced for example by the impregnation of an aqueous solution ofhydrofluoric acid or of ammonium fluoride.

The catalysts used in the process according to the invention areadvantageously in the form of spheres or extrudates. It is howeveradvantageous for the catalyst to be in the form of extrudates with adiameter between 0.5 and 5 mm and more particularly between 0.7 and 2.5mm. The shapes are cylindrical (which can be hollow or solid),cylindrical twisted, multilobed (2, 3, 4 or 5 lobes for example), rings.The cylindrical shape is preferably used, but any other shape can beused. The catalysts according to the invention can optionally bemanufactured and used in the form of crushed powder, pellets, rings,beads, or wheels.

According to the invention, the metals of group VIB and/or non-preciousmetals of group VIII of said catalyst are present in the form ofsulphide, the sulphurization treatment being described later.

The invention also relates to a process for hydrocracking and/orhydrotreatment of hydrocarbon feeds using the catalyst described above.

Hydrocracking and Hydrotreatment Processes

The invention relates to a hydrocracking and/or hydrotreatment processoperating in the presence of hydrogen, at a temperature greater than200° C., at a pressure greater than 1 MPa, the space velocity beingbetween 0.1 and 20 h⁻¹ and the quantity of hydrogen introduced is suchthat the volume ratio liter of hydrogen/liter of hydrocarbon is between80 and 5000 L/L.

More particularly, the invention relates to a process of hydroconversionand in particular of hydrocracking as well as to a process ofhydrotreatment of hydrocarbon feeds using the catalyst described above.

Preferably, the hydrocracking process according to the inventionoperates in the presence of hydrogen, at a temperature greater than 200°C., preferably between 250 and 480° C., preferably between 320 and 450°C., very preferably between 330 and 435° C., at a pressure greater than1 MPa, preferably between 2 and 25 MPa, more preferably between 3 and 20MPa, at a space velocity between 0.1 and 20 h⁻¹, preferably 0.1 and 6h⁻¹, preferably between 0.2 and 3 h⁻¹, and the quantity of hydrogenintroduced is such that the volume ratio liter of hydrogen/liter ofhydrocarbon is between 80 and 5000 L/L and generally between 100 and2000 L/L.These operating conditions used in the processes according to theinvention generally make it possible to reach conversions per pass, toproducts having boiling points less than 340° C., and preferably lessthan 370° C., greater than 15 wt. % and even more preferably between 20and 95 wt. %.

The invention also relates to a process of hydrotreatment of hydrocarbonfeeds using the catalyst described above, and said process ofhydrotreatment can advantageously be installed alone or upstream of ahydrocracking process. Said hydrotreatment process is described later.

Feeds

Very varied feeds can be treated by the processes according to theinvention described above. Advantageously they contain at least 20 vol.% and preferably at least 80 vol. % of compounds boiling greater than340° C.

The feed is advantageously selected from LCO (Light Cycle Oil=lightdiesel fuels obtained from a catalytic cracking unit), atmosphericdistillates, vacuum distillates such as for example gas oils from directdistillation of crude or from conversion units such as FCC, coking orvisbreaking units, feeds obtained from units for extracting aromaticsfrom bases of lubricating oil or obtained from solvent dewaxing of basesof lubricating oil, distillates from fixed-bed or ebullating-bedprocesses of desulphurization or hydroconversion of AR (atmosphericresidues) and/or of VR (vacuum residues) and/or of deasphalted oils, andthe deasphalted oils, used alone or in a mixture. The above is not anexhaustive list. The paraffins resulting from the Fischer-Tropschprocess are excluded. Said feeds preferably have a boiling point T5greater than 340° C., preferably greater than 370° C., i.e. 95% of thecompounds present in the feed have a boiling point greater than 340° C.,and preferably greater than 370° C.

The nitrogen content of the feeds treated in the processes according tothe invention is advantageously greater than 500 ppm by weight,preferably between 500 and 10000 ppm by weight, more preferably between700 and 4000 ppm by weight and even more preferably between 1000 and4000 ppm by weight. The sulphur content of the feeds treated in theprocesses according to the invention is advantageously between 0.01 and5 wt. %, preferably between 0.2 and 4 wt. % and even more preferablybetween 0.5 and 3 wt. %.

The feed can optionally contain metals. The cumulative content of nickeland vanadium in the feeds treated in the processes according to theinvention is preferably less than 1 ppm by weight.

The feed can optionally contain asphaltenes. The content of asphaltenesis generally less than 3000 ppm by weight, preferably less than 1000 ppmby weight, even more preferably less than 200 ppm by weight.

Sulphurization of the Catalysts

According to the invention, prior to injection of the feed, thecatalysts used in the processes according to the present invention aresubjected beforehand to a sulphurization treatment for converting, atleast partly, the metallic species to sulphide before bringing them intocontact with the feed to be treated. This treatment of activation bysulphurization is well known to a person skilled in the art and can becarried out by any method already described in the literature eitherin-situ, i.e. in the reactor, or ex-situ.

A conventional method of sulphurization that is well known to a personskilled in the art consists of heating the catalyst in the presence ofhydrogen sulphide (pure or for example under a stream of ahydrogen/hydrogen sulphide mixture) at a temperature between 150 and800° C., preferably between 250 and 600° C., generally in atraversed-bed reaction zone.

Guard Beds

In the case where the feed contains compounds of the resin and/orasphaltene type, it is advantageous for the feed to be passed first overa bed of catalyst or of adsorbent different from the hydrocracking orhydrotreatment catalyst. The guard catalysts or beds used according tothe invention are in the form of spheres or extrudates. It is howeveradvantageous for the catalyst to be in the form of extrudates with adiameter between 0.5 and 5 mm and more particularly between 0.7 and 2.5mm. The shapes are cylindrical (which can be hollow or solid),cylindrical twisted, multilobed (2, 3, 4 or 5 lobes for example), orrings. The cylindrical shape is preferably used, but any other shape canbe used.

In order to remedy the presence of contaminants and/or poisons in thefeed, guard catalysts can, in another preferred embodiment, have moreparticular geometric shapes in order to increase their voids fraction.The voids fraction of these catalysts is between 0.2 and 0.75. Theiroutside diameter can vary between 1 and 35 mm. Among the possibleparticular shapes, without this list being exhaustive, there may bementioned: hollow cylinders, hollow rings, Raschig rings, notched hollowcylinders, indented hollow cylinders, pentaring cartwheels, cylinderswith multiple holes, etc.

These guard catalysts or beds can have been impregnated with an activeor inactive phase. Preferably, the catalysts are impregnated with ahydrogenating-dehydrogenating phase. Very preferably, the phase CoMo orNiMo is used.

These guard catalysts or beds can have macroporosity. The guard beds canbe those marketed by Norton-Saint-Gobain, for example the MacroTrap®guard beds. The guard beds can be those marketed by Axens in the ACTfamily: ACT077, ACT645, ACT961 or HMC841, HMC845, HMC868 or HMC945. Itcan be particularly advantageous to superpose these catalysts in atleast two different beds with variable heights. The catalysts with thehighest voids fraction are preferably used in the first catalyst bed(s)at the entrance of the catalytic reactor. It can also be advantageous touse at least two different reactors for these catalysts.

The guard beds that are preferred according to the invention are theHMCs and ACT961.

EMBODIMENTS

The hydrocracking processes according to the invention using thecatalysts described above cover the ranges of pressure and conversionfrom mild hydrocracking to high-pressure hydrocracking. By “mildhydrocracking” is meant hydrocracking leading to moderate conversions,generally less than 40%, and operating at low pressure, generallybetween 2 MPa and 6 MPa.

The hydrocracking processes according to the invention canadvantageously use said catalyst described above alone, in one or morefixed-bed catalyst beds, in one or more reactors, in a hydrocrackingscheme called single-stage, with or without liquid recycling of theunconverted fraction, optionally in combination with a conventionalhydrotreatment catalyst located upstream of the catalyst used in theprocess according to the present invention.

The hydrocracking processes according to the invention canadvantageously also use said catalyst described above alone, in one ormore ebullating bed reactors, in a hydrocracking scheme calledsingle-stage, with or without liquid recycling of the unconvertedfraction, optionally in combination with a conventional hydrotreatmentcatalyst located in a fixed-bed or ebullating-bed reactor upstream ofthe catalyst used in the process according to the present invention.

The ebullating bed operates with withdrawal of spent catalyst and dailyaddition of fresh catalyst in order to maintain stable catalystactivity.

The catalyst described according to the invention can alsoadvantageously be used in the first hydrotreatment reaction zone, inconverting pretreatment, alone or in combination with anotherconventional hydrorefining catalyst, located upstream of the catalystdescribed according to the invention, in one or more catalyst bed(s), inone or more fixed-bed or ebullating-bed reactor(s).

The So-Called Single-Stage Process

The hydrocracking process according to the invention can advantageouslybe used in a so-called single-stage process.

So-called single-stage hydrocracking comprises firstly and generally asevere hydrorefining which has the purpose of carrying out a severehydrodenitrogenation and desulphurization of the feed before the latteris sent over the hydrocracking catalyst proper, particularly in the casewhere the latter comprises a zeolite. This severe hydrorefining of thefeed only results in limited conversion of the feed, to lighterfractions, which is still insufficient and must therefore be completedon the more active hydrocracking catalyst described above. However, itis to be noted that no separation occurs between the two types ofcatalysts. All of the effluent leaving the reactor is injected onto thehydrocracking catalyst proper, and it is only thereafter that theproducts formed are separated. This version of hydrocracking, alsocalled “Once Through”, includes a variant with recycling of theunconverted fraction to the reactor for deeper conversion of the feed.

The catalyst described according to the invention is thereforeadvantageously used in a single-stage hydrocracking process, in ahydrocracking zone located downstream of a hydrorefining zone, withoutapplying any intermediate separation between the two zones.

Preferably, the hydrorefining catalyst used in the first hydrorefiningreaction zone, alone or in combination with another conventionalhydrorefining catalyst, located upstream of the catalyst describedaccording to the invention, is a catalyst optionally comprising a dopingelement selected from phosphorus, boron and silicon, said catalyst beingbased on non-precious group VIII elements and optionally in combinationwith group VIB elements on an alumina or silica-alumina support and evenmore preferably said catalyst comprises nickel and tungsten.

The catalyst described according to the invention can also be usedadvantageously in the first hydrorefining reaction zone, in convertingpretreatment, alone or in combination with another conventionalhydrorefining catalyst, located upstream of the catalyst describedaccording to the invention, in one or more catalyst bed(s), in one ormore reactor(s).

So-Called Single-Stage Fixed-Bed Process with Intermediate Separation

The hydrocracking process according to the invention can advantageouslybe implemented in a so-called single-stage fixed-bed process withintermediate separation.

Said process advantageously comprises a hydrorefining zone, a zonepermitting partial removal of ammonia, for example by hot flash, and azone comprising said hydrocracking catalyst according to the invention.This process for single-stage hydrocracking of hydrocarbon feeds for theproduction of middle distillates and optionally of oil basesadvantageously comprises at least one first hydrorefining reaction zone,and at least one second reaction zone, in which the hydrocracking of atleast a proportion of the effluent from the first reaction zone takesplace. This process also comprises advantageously an incompleteseparation of the ammonia from the effluent leaving the first zone. Thisseparation is advantageously carried out by means of an intermediate hotflash. The hydrocracking taking place in the second reaction zone isadvantageously carried out in the presence of ammonia in a quantity lessthan the quantity present in the feed, preferably less than 1500 ppm byweight, more preferably less than 1000 ppm by weight and even morepreferably less than 800 ppm by weight of nitrogen.

The catalyst described according to the invention is thereforeadvantageously used in a single-stage fixed-bed hydrocracking processwith intermediate separation, in a hydrocracking zone located downstreamof a hydrorefining zone, an intermediate separation for partial removalof ammonia being applied between the two zones.

Preferably, the hydrorefining catalyst used in the first hydrorefiningreaction zone, alone or in combination with another conventionalhydrorefining catalyst, located upstream of the catalyst describedaccording to the invention, is a catalyst optionally comprising a dopingelement selected from phosphorus, boron and silicon, said catalyst beingbased on non-precious group VIII elements and optionally in combinationwith group VIB elements on an alumina or silica-alumina support and evenmore preferably said catalyst comprises nickel and tungsten.

The catalyst described according to the invention can alsoadvantageously be used in the first hydrorefining reaction zone, inconverting pretreatment, alone or in combination with anotherconventional hydrorefining catalyst, located upstream of the catalystdescribed according to the invention, in one or more catalyst bed(s), inone or more reactor(s).

So-Called Two-Stage Process

The hydrocracking process according to the invention can advantageouslybe used in a so-called two-stage process.

Two-stage hydrocracking comprises a first stage, which has the purpose,as in the “single-stage” process, of performing hydrorefining of thefeed, but also of achieving a conversion of the latter generally of theorder of 40 to 60%. The effluent from the first stage then undergoes aseparation (distillation) that is usually called intermediateseparation, which has the purpose of separating the conversion productsfrom the unconverted fraction. In the second stage of a two-stagehydrocracking process, only the fraction of feed not converted duringthe first stage is treated. This separation allows a two-stagehydrocracking process to be more selective for middle distillates(kerosene+ diesel) than a single-stage process. In fact, intermediateseparation of the conversion products avoids their “over-cracking” tonaphtha and gases in the second stage on the hydrocracking catalyst.Moreover, it should be noted that the unconverted fraction of the feedtreated in the second stage generally has very low contents of NH₃ aswell as organic nitrogen-containing compounds, generally less than 20ppm by weight or even less than 10 ppm by weight.

The configurations of fixed-bed or ebullating-bed catalyst bedsdescribed in the case of a so-called single-stage process canadvantageously be used in the first stage of a two-stage scheme, whetherthe catalyst according to the invention is used alone or in combinationwith a conventional hydrorefining catalyst.

The catalyst described according to the invention is thereforeadvantageously used in a so-called two-stage hydrocracking process, inthe second hydrocracking stage located downstream of the first stage ofhydrorefining, an intermediate separation being used between the twozones.

For the so-called single-stage processes and for the first hydrorefiningstage of two-stage hydrocracking processes, the conventionalhydrorefining catalysts that can be used advantageously are catalystsoptionally comprising a doping element selected from phosphorus, boronand silicon, said catalyst being based on non-precious group VIIIelements and optionally in combination with group VIB elements on analumina or silica-alumina support and even more preferably said catalystcomprises nickel and tungsten.

Hydrotreatment/Hydrorefining of Hydrocarbon Feeds

The invention also relates to a process for hydrotreatment ofhydrocarbon feeds using the catalyst described above, and saidhydrotreatment process can advantageously be installed alone or upstreamof a hydrocracking process.

The hydrotreatment and hydrorefining of hydrocarbon feeds such aspetroleum fractions, fractions obtained from coal or hydrocarbonsproduced from natural gas relate to hydrogenation,hydrodesulphurization, hydrodenitrogenation, hydrodeoxygenation,hydrodearomatization and hydrodemetallation of hydrocarbon feedscontaining aromatic and/or olefinic and/or naphthenic and/or paraffiniccompounds, said feeds optionally containing metals and/or nitrogenand/or oxygen and/or sulphur.

More particularly, the feeds used in the hydrotreatment processesaccording to the invention are gasolines, gas oils, vacuum gas oils,atmospheric residues, vacuum residues, atmospheric distillates, vacuumdistillates, heavy fuels, oils, waxes and paraffins, used oils,deasphalted residues or crudes, feeds obtained from thermal or catalyticconversion processes and mixtures thereof. They preferably containheteroatoms such as sulphur, oxygen and nitrogen and/or at least onemetal.

The hydrotreatment process according to the invention advantageouslyoperates at a temperature between 200 and 450° C., preferably between250 and 440° C., at a pressure between 1 and 25 MPa, preferably between1 and 18 MPa, at a hourly space velocity between 0.1 and 20 h⁻¹,preferably between 0.2 and 5⁻¹, and at a hydrogen/feed ratio expressedin volume of hydrogen, measured under standard conditions of temperatureand pressure, per volume of liquid feed generally between 80 L/L and5000 L/L and preferably between 100 L/L and 2000 L/L.

In the case where said hydrotreatment process is installed alone orupstream of a hydrocracking process, the catalyst described according tothe invention can advantageously be used in the hydrotreatment reactionzone, in converting pretreatment, alone or in combination with anotherconventional hydrotreatment catalyst, located upstream of the catalystdescribed according to the invention, in one or more catalyst bed(s), inone or more reactor(s). The catalyst used in the hydrocracking processlocated downstream of the hydrotreatment process according to theinvention can advantageously be identical to or different from thecatalyst used in the hydrotreatment process according to the invention.

EXAMPLES Example 1 Preparation of Z1 the Dealuminated Initial Zeolite YAccording to the Invention

100 g of zeolite NaY raw from synthesis is exchanged 3 times with a 1 Nsolution of NH₄NO₃ at a temperature of 80° C., obtaining zeolite NH₄Y.The zeolite NH₄Y then undergoes a thermal treatment at 700° C. for 3 hin the presence of 60% of steam. The thermal treatment is carried outusing a gas stream formed from steam and air of 2 L/h/g of zeolite. Thezeolite is then treated with a solution of 2 mol/L of HNO₃ (V/W=15) for3 h at 80° C. The zeolite is finally filtered and dried for 12 h at 120°C. The zeolite is then in the dealuminated form HY.

The dealuminated zeolite HY obtained Z1 has an overall atomic ratioSi/Al=6.2 measured by X-ray fluorescence, an initial weight fraction ofextra-lattice aluminium atoms equal to 37 wt. % relative to the totalweight of aluminium present in the zeolite and measured by NMR of thealuminium, an initial mesopore volume measured by nitrogen porosimetryequal to 0.15 ml·g⁻¹, and an initial crystal lattice parameter a₀ equalto 24.35 Å, measured by XRD.

Example 2 Preparation of Z2 the Dealuminated Zeolite Y not According tothe Invention

The zeolite Z1 prepared in Example 1 undergoes a second series ofthermal treatment in the presence of steam and an acid attack treatmentby washing with acid. The second thermal treatment is carried out at750° C. using 80% of steam and the solution of acid used is 5 mol/L for5 h.

The dealuminated zeolite HY Z2 has an overall atomic ratio Si/Al=25.4measured by X-ray fluorescence, an initial weight fraction ofextra-lattice aluminium atoms equal to 12 wt. % relative to the totalweight of aluminium present in the zeolite measured by NMR of thealuminium, an initial mesopore volume measured by nitrogen porosimetryequal to 0.18 ml·g⁻¹, and an initial crystal lattice parameter a₀ equalto 24.25 Å, measured by XRD.

Example 3 Preparation of Z3 the Modified Zeolite According to theInvention Used in the Catalyst According to the Invention

100 g of dealuminated zeolite HY Z1 with overall atomic ratio Si/Al=6.2measured by XF prepared in Example 1 is mixed with 1 L of a 0.1 Nsolution of sodium hydroxide (NaOH) at 60° C. for 30 min. After rapidcooling in ice water, the suspension is then filtered and the zeolite iswashed at 50° C. and dried overnight at 120° C. The modifieddealuminated zeolite Y is then exchanged 3 times with a 1 N solution ofNH₄NO₃ at a temperature of 80° C., obtaining the partially exchangedform NH₄ ⁺. Finally the zeolite is calcined at 450° C. for 2 h under anair stream of 1 L/h/g of zeolite. The characteristics of the zeolite Z3measured by adsorption/desorption of nitrogen, X-ray fluorescence, NMRof ²⁷Al and of ²⁹Si and by adsorption of pyridine followed by IR areshown in Table 1.

Example 4 Preparation of Z4 the Modified Zeolite not According to theInvention

100 g of the dealuminated zeolite Y Z2 with overall Si/Al ratio equal to25.4 is mixed with 1 of a 0.3 N solution of sodium hydroxide at 60° C.for 1.5 h. After rapid cooling in ice water, the suspension is thenfiltered and the zeolite is washed at 50° C. and dried overnight at 120°C. The modified dealuminated zeolite Y is then exchanged 3 times with a1 N solution of NH₄NO₃ at a temperature of 80° C., obtaining thepartially exchanged form NH₄ ⁺. Finally the zeolite is calcined at 450°C. for 2 h under an air stream of 1 L/h/g of zeolite. Thecharacteristics of the zeolite Z4 measured by adsorption/desorption ofnitrogen, X-ray fluorescence, NMR of ²⁷Al and of ²⁹Si and by adsorptionof pyridine followed by IR are shown in Table 1.

TABLE 1 Characterization of the samples initial initial modifiedunmodified unmodified modified zeolite zeolite Z1 zeolite Z2 not zeoliteZ3 Z4 not according to according to according to according to theinvention the invention the invention the invention Overall 6.2 25.4 4.713.8 Si/Al (XF) % Al_(VI) 37 12 33 13 (NMR) S_(BET) (m²/g) 778 791 743709 Mesopore 0.15 0.18 0.28 (+86%) 0.30 (+72%) volume (ml/g) Micropore0.28 0.27 0.25 (−11%) 0.14 (−44%) volume (ml/g) Brønsted 4.3 2.1  5.4(+25%)  1.9 (−10%) acidity (a.u.)

Example 5 Preparation of the Catalysts

The catalyst supports according to the invention containing the modifiedzeolites (Z3 and Z4) or unmodified zeolites (Z1 and Z2) are made using18.5 g of zeolite mixed with 81.5 g of a matrix composed of ultrafinetabular boehmite or alumina gel marketed under the name SB3 by thecompany Condea Chemie GmbH. This mixture of powder is then mixed with anaqueous solution containing nitric acid at 66 wt. % (7 wt. % of acid pergram of dry gel) and then kneaded for 15 minutes. The kneaded paste isthen extruded through a die with a diameter of 1.2 mm. The extrudatesare then calcined at 500° C. for 2 hours in air.

The extrudates of support thus prepared are subjected to dryimpregnation with a solution of a mixture of ammonium heptamolybdate andnickel nitrate and are calcined in air at 550° C. in-situ in thereactor. The catalysts C1, C2, C3 and C4 are thus prepared from theunmodified zeolites Z1 and Z2 and from the zeolites Z3 and Z4,respectively. The contents by weight of oxides in the catalysts obtainedare shown in Table 2.

TABLE 2 Characteristics of the catalysts Catalyst reference C1 C2 C3 C4(not according (not according (according to (not according to theinvention) to the invention) the invention) to the invention) Zeolite onwhich the catalyst is based Z3 Z1 Z2 modified according Z4 unmodifiedunmodified to the invention modified MoO₃ (wt. %) 12.3 12.2 12.3 12.0NiO (wt. %) 3.0 3.3 3.1 3.0 Total SiO₂ (wt. %) 14.3 14.1 13.9 14.1Remainder to 70.4 70.4 70.7 70.9 100% (mainly composed of Al₂O₃ (wt. %)

Example 6 Comparison of the Catalysts in Single-Stage Hydrocracking of aVacuum Distillate

The catalysts the preparation of which was described in the precedingexamples are used under the conditions of high-conversion hydrocracking(60-100%). The petroleum feed is a vacuum distillate that has undergonea first stage of hydrorefining on a catalyst with the principalcharacteristics shown in Table 3.

No stage of intermediate separation is used between the previoushydrorefining stage and the hydrocracking stage.

TABLE 3 Characteristics of the feed used Density (20/4) 0.869 Sulphur(ppm by weight) 502 Nitrogen (ppm by weight) 10 Simulated distillationinitial point 298° C. 10% point 369° C. 50% point 427° C. 90% point 481°C. end point 538° C.

0.6 wt. % of aniline and 2 wt. % of dimethyl disulphide are added to thefeed to simulate the H₂S and NH₃ partial pressures present in the secondstage of hydrocracking. The feed thus prepared is injected into thehydrocracking test unit, which comprises a fixed-bed reactor, withascending (“up-flow”) circulation of the feed, in which 80 ml ofcatalyst is introduced. The catalyst is sulphurized with ann-hexane/DMDS+aniline mixture up to 320° C. Note that any method ofin-situ or ex-situ sulphurization is suitable. Once the sulphurizationhas been carried out, the feed described in Table 3 can be converted.The operating conditions of the test unit are presented in Table 4.

TABLE 4 Catalyst testing conditions Total pressure 9 MPa Catalyst 80 cm³Hydrogen flow rate 80 L/h Feed flow rate 80 cm³/h

The catalytic performance is expressed by the temperature that allows araw conversion level of 70% to be reached and by the yields of gasolineand jet fuel (kerosene). This catalytic performance is measured on thecatalyst after a period of stabilization, generally of at least 48hours.

The raw conversion RC is put equal to:RC=wt. % of 380° C. minus of the effluentwith “380° C. minus” representing the fraction distilled at atemperature less than or equal to 380° C.

The yield of jet fuel (kerosene, 150-250, shown below as Yield Kero) isequal to the percentage by weight of compounds having a boiling pointbetween 150 and 250° C. in the effluents. The yield of diesel fuel(250-380) is equal to the percentage by weight of compounds having aboiling point between 250 and 380° C. in the effluents.

The reaction temperature is fixed so as to reach a raw conversion RCequal to 70 wt. %. Table 5 shows the reaction temperature and the yieldsof light and middle distillates for the catalysts described in theexamples given above.

TABLE 5 Catalytic activities of the catalysts in hydrocracking TKerosene yield Diesel fuel yield (° C.) (wt. %) (wt. %) C1 not accordingto the 386 23.9 19.3 invention (prepared from unmodified Z1) C2 notaccording to the 391 19.9 17.2 invention (prepared from unmodified Z2)C3 according to the invention 384 24.1 22.4 (prepared from Z3 modifiedaccording to the invention) C4 not according to the 393 20.3 18.2invention (prepared from modified Z4)

Catalyst C3 prepared with the modified zeolite Z3 according to theinvention gives an activity in hydroconversion of vacuum distillate anda selectivity for middle distillates (kerosene+diesel fuel) that aregreatly improved relative to catalysts C2 and C4 respectively, whereinC2 is prepared from an unmodified zeolite Z2 and not having the requiredoverall Si/Al ratio and C4 is prepared from the modified zeolite Z4(i.e., a modified zeolite prepared from Z2). Catalyst C3 also hasgreatly improved activity and selectivity relative to catalyst C1prepared from the unmodified initial zeolite Z1.

The entire disclosures of all applications, patents and publications,cited herein and of corresponding French application No. 09/05.404,filed Nov. 10, 2009 are incorporated by reference herein.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

The invention claimed is:
 1. A process for modifying a dealuminatedzeolite Y comprising: a basic treatment stage wherein said dealuminatedzeolite Y is mixed with a basic aqueous solution, said basic aqueoussolution being a solution of basic compounds selected from alkali metalcarbonates and alkali metal hydroxides, wherein said basic treatmentstage is carried out at a temperature between 40 and 100° C. and for aduration between 5 minutes and 5 hours; a partial exchange stage wherein85 to 99.5% of alkaline cations, introduced during said basic treatmentstage, are exchanged with NH₄ ⁺ cations, whereby the remaining contentof alkaline cations is such that the molar ratio of alkaline cations toaluminum is between 0.15:1 and 0.005:1; and at least one thermaltreatment stage which is carried out at a temperature between 200 and700° C.
 2. A process according to claim 1, wherein said dealuminatedinitial zeolite Y has, before it is modified, an overall initial atomicratio of silicon to aluminum between 2.7 and 10.0.
 3. A processaccording to claim 1, wherein said dealuminated initial zeolite Y has,before it is modified, an initial weight fraction of extra-latticealuminum atoms greater than 30 wt. % relative to the total weight ofaluminum present in the zeolite.
 4. A process according to claim 1,wherein the resultant modified dealuminated zeolite Y has a finalmesopore volume measured by nitrogen porosimetry at least 10% greaterrelative to the initial mesopore volume of the initial dealuminatedzeolite Y, a final micropore volume measured by nitrogen porosimetrythat is not decreased by more than 40%, relative to the initialmicropore volume of said the initial dealuminated zeolite Y, a Brønstedacidity more than 10% higher relative than the Brønsted acidity of theinitial dealuminated zeolite Y, and a final crystal lattice parameter a₀greater than the initial crystal lattice parameter a₀ of the initialdealuminated zeolite Y.
 5. The process according to claim 1, in which,before being modified, the dealuminified Y zeolite has an initialoverall atomic ratio of silicon to aluminum of between 2.6 and 12.0. 6.The process according to claim 1, in which, before being modified, thedealuminified Y zeolite has a starting extra-lattice aluminum atomfraction by weight that is greater than 20% by weight relative to thetotal mass of the aluminum that is present in the zeolite.
 7. Theprocess according to claim 1, in which, before being modified, thedealuminified Y zeolite has a mesopore volume, measured by nitrogenporosimetry, of greater than 0.10 ml·g⁻¹.
 8. The process according toclaim 1, in which, before being modified, the dealuminified Y zeolitehas a mesopore volume, measured by nitrogen porosimetry, of greater than0.13 ml·g⁻¹.
 9. The process according to claim 1, in which, before beingmodified, the dealuminified Y zeolite has a mesopore volume, measured bynitrogen porosimetry, of greater than 0.20 ml·g⁻¹.
 10. The processaccording to claim 1, in which, before being modified, the dealuminifiedY zeolite has a mesopore volume, measured by nitrogen porosimetry, ofgreater than 0.25 ml·g⁻¹.
 11. The process according to claim 1, inwhich, after being modified, the dealuminified Y zeolite has a mesoporevolume, measured by nitrogen porosimetry, that is greater than at least10% relative to the mesopore volume before modification.
 12. The processaccording to claim 1, in which, after being modified, the dealuminifiedY zeolite has a mesopore volume, measured by nitrogen porosimetry, thatis greater than at least 20% relative to the mesopore volume beforemodification.
 13. The process according to claim 1, wherein prior tobeing modified the dealuminated zeolite Y has an overall initial atomicratio of silicon to aluminum between 2.5 and 20, an initial weightfraction of extra-lattice aluminum atoms greater than 10%, relative tothe total weight of aluminum present in the zeolite, an initial mesoporevolume measured by nitrogen porosimetry greater than 0.07 ml·g⁻¹, and aninitial crystal lattice parameter a₀ between 24.38 Å and 24.30 Å. 14.The process according to claim 1, wherein after the partial exchangestage the molar ratio of alkaline cations to aluminum is between 0.12:1and 0.01:1.
 15. The process according to claim 1, wherein the partialexchange is performed under the following conditions: anNH₄+concentration of 1 and 10 mol/L in the exchange solution, attemperature of 60 and 95° C., and a cation exchange number of between 1and 4.